Hi guys, I'm looking for a little advice on cheap wide angle prime lenses. Basically, I've revived my old 20D and I'm wanting a cheap prime lens that I can carry around on it and use as my knock about camera. I'm envisioning this camera will carried around into the ocean and other non camera friendly places, so my reasoning for cheap is that there is a possibility of it getting destroyed. I'm looking for something preferably wider then 24mm to compensate for the crop factor and I'm not fussed by brand or quality too much. Any suggestions?